The overall objective of this research project is to investigate the functional organization and regulation of a small section of the genome (13 genes) of Drosophila melanogaster and in particular investigate in detail the genetic regulation of one of those genes during development. This research project will provide important new information on how genes are regulated in a higher organism and thereby provide a basis for the study of abnormal development such as inherited developmental defects and the uncontrolled growth of cancer cells. The activity of this gene, Ddc, which codes for the enzyme dopa decarboxylase, DDC, is required in the epidermis at five stages in development for sclerotization (hardening) the cuticle, in the ovary for female fertility, and in the nervous system for the production of the neurotransmitter, dopamine and serotonin. Emphasis will be placed on tissue specific and stage specific regulation of Ddc, although overproducer and underproducer regulator mutations will also be studied. Fourt ovary specific regulator mutations will be characterized and the DNA sequence altered determined. Nervous system specific and stage specific regulator mutation will be sought, characterized, and the DNA sequences altered determined. An important question to be answered is whether or not the same or different sequences are altered by the different types of tissue and stage specific mutations. -- We will isolate Ddc specific DNA binding proteins, determine the sequences to which they bind, and ask if the tissue and stage specific regulator mutations alter these sequences. -- We will determine if these regulator mutations are involved in a phenomenon best described as synapsis dependent intragenic transcriptional complementation (transregulation? transvection?). --Ddc is located in the midst of a cluster of functionally related and perhaps coordinately controlled genes involved in the formation and sclerotization of cuticle and female fertility. We will continue to elucidate the genetic and molecular organization of this region of the genome. We will determine how the function of each gene contributes to cuticle formation and/or female fertility, determine what protein (enzyme) is specified by each gene, and investigate the possible coordinate of these genes.